This invention relates to apparatus for indicating when a preselected capacity of a recording medium upon which messages are recorded in a recording system has been used and, more particularly, to such an apparatus wherein the preselected capacity is a variable percentage of the total capacity of the recording medium, and wherein the recording medium is replaced automatically with a fresh medium when such preselected capacity has been used.
In recording systems wherein messages such as audio information are recorded on a medium of finite length, or capacity, it often is advantageous to apprise an operator of that system when the capacity of the medium is or soon will be reached. This is particularly advantageous when the messages are dicated information, so that the operator is prepared to replace the recording medium with a fresh medium and thus continue dictation without loss of information and without serious interruption in the overall dictation operation.
When the recording system is of the so-called central-type of system, a central record/playback unit generally is adapted to communicate with an individual one of multiple remote dictate stations. If an operator at a remote dictate station establishes communication with or, "seizes" the central unit, whereat the recording medium has remaining only a small percentage of its total capacity for the recording of additional dictated messages, there is a strong possibility that the operator then communicating with the central unit will be unable to complete his message on such remaining portion of the medium. Hence, it is desirable to furnish that operator with an indication that only a small percentage of the recording capacity of the medium is available to him and, preferably, to avoid the occurrence of such a situation. When the recording medium is constituted by a recording belt, such as a permanent recording belt or a magnetic belt, or by a magnetic disc or by magnetic tape, the aforementioned situation can be substantially avoided by automatically replacing the recording medium with a fresh medium once a predetermined capacity of the medium has been attained and prior to the establishment of communication between a remote dictate station and the central unit. Thus, when only a small recording capacity remains, the recording medium, e.g., the belt, disc, or tape, will be replaced before the next seizure of the central unit, thereby assuring that the next operator will be furnished with a medium that is substantially capable of recording his entire message.
As may be appreciated, the expected length of a typical message may vary, depending upon the particular operator, the environment of the recording system and the general usage thereof. For example, when a typical dicated message is relatively brief, the recording medium of finite length can be expected to have multiple messages recorded thereon. Conversely, when the typical dictated message is relatively long, the recording medium will exhibit a capacity for relatively few messages. Therefore, it is desirable to permit an operator, or supervisor, of the recording system to select, or preset, the relative capacity of the medium. For example, if the medium has a 30-minute recording capacity, and if the typical dictated message is approximately 3 minutes, then the relative capacity of the medium may be selected at 20-24 minutes so as to reasonably insure that most of the medium will be used economically, but that it will not be exhausted while a dictation operation is in progress. Once this preselected amount of recording is achieved, the recording medium then can be replaced once the dictation operation then in progress has been completed. As another example, if it is of primary importance to prevent the exhaustion of the recording medium during a dictation operation, the preset capacity can be reduced to a relatively lower percentage of the full recording capacity.
As yet another example of establishing a preselected capacity of the recording medium, this preselection may be determined as a function of individual messages that are recorded. Then, assuming that the expected length of each message is known, the number of individually recorded messages can be counted until the preset number is reached. Typically, successive messages can be distinguished by providing a start-of-message signal, or equivalent, immediately prior to the actual message. In one embodiment of a central recording system, the equivalent of a start-of-message signal is produced whenever a remote station seizes the central unit.
It is believed that, in most instances, a more efficient use of the recording medium is achieved by establishing the preselected capacity thereof as a function of its length. Since the effective length of a recording medium usually is interpreted as the time-related quantity of messages that can be recorded, the preselected recording capacity can be established as a function of recording time. However, in order to achieve greater flexibility, it is advantageous to provide a dual measure of recording capacity, e.g., as a percentage of the total recording time of the medium or as a number of recorded messages, both effectively representing the amount of recording medium that can be used.